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Just What Is a Standard Drink, Anyway?

Earlier this year in Pursuit of Hoppiness, I said that moderation was going to be the theme of my beer writing in 2018. I (safely) assumed that most who were reading the piece would have fallen asleep before the end of it; but in the days that followed the release of the issue, I received several messages from those with whom the message resonated – folk who were also searching for a more moderate and regret-free relationship with alcohol. So safe in the knowledge that at least six people will still be reading by the end of this paragraph, I want to spend this issue talking about Standard Drinks.

In order to move towards a healthy relationship with booze, I believe our first step is to plot our current coordinates with respect to that objective. Once we have established our whereabouts, we can then start moving vaguely toward the goal – all the while continuing to measure our position from week-to-week, to make sure that we’re not veering wildly off-course. When it comes to measuring our position, we’re rather lucky in this context to have a relatively-robust unit of measurement that can help us out: the good-old Standard Drink.

The math used to calculate a Standard Drink is simple enough – but for sheer fun (and the possibility of setting a first for Pursuit of Hoppiness), I’ll present it as a formula:

Number of Standard Drinks = V x P x 0.789

where V = the volume of the drink in litres; P = the percentage alcohol in the drink (ABV is fine); and 0.789 = a constant (related to grams of alcohol in the drink, and how long our body will take to process it – but we’ll get to that in minute). Using beers from my beloved 8 Wired as an example, the number of Standard Drinks in a 330ml bottle of Hippy Berliner is:

0.33 x 4 x 0.789 = 1.0

while the formula for the same-size bottle of iStout is:

0.33 x 10 x 0.789 = 2.6

We all get the gist of what a Standard Drink is – the bigger the number, the boozier the booze – but what does this number actually mean? Is the Standard Drinks value entirely arbitrary, or is there some actual meaning behind it? After a bit of digging, I’ve discovered that the answer to that question – rather inevitably – is both.

In New Zealand, one Standard Drink – that 330ml bottle of Hippy Berliner – contains the equivalent of 10 grams of pure ethanol (ethanol being the main alcohol present in alcoholic drinks). New Zealand follows the World Health Organisation recommendations in this respect, as do many of our usual comrades (including Australia). However, there are some notable exceptions: in the United States, one Standard Drink is equivalent to 14 grams of pure ethanol; while in the United Kingdom it’s only 8 grams. Much of this variation is driven by disagreements regarding the threshold for how many grams of ethanol an ‘average’ person can metabolise over the course of an hour – defining an ‘average person’ is a headache in itself – but some countries ignore the biochemistry and set their Standard Drink to reflect the typical serving size consumed by their citizens. In Austria, for example, one Standard Drink is equivalent to a 500ml pint of 5% beer – think: tall handles of Stiegl at a bierhaus in Salzburg – which will contain 20 grams of pure ethanol.

While there are some arbitrary elements at play here (deciding on one universal amount of ethanol that can be metabolised within an hour, for instance), there is at least some semblance of thought and meaning behind this unit. It actually is important to know how much ethanol you are biffing into your body over a given period of time, since the way your body deals with this stuff is neither straightforward nor particularly fast. And when it comes to the NZ/WHO definition of a standard drink, understanding how this process works is inherent to understanding how a Standard Drink is calculated.

The vast majority (>90%) of the ethanol that you consume will be metabolised by your liver. The most common way this happens is via a two-step process: firstly, a clever enzyme called alcohol dehydrogenase breaks the ethanol down to a highly-toxic compound called acetaldehyde – a substance well-known to homebrewers as the fault that makes our beer taste like green apples – and then another clever enzyme (aldehyde dehydrogenase) further metabolises the acetaldehyde into acetate. Finally, the acetate is converted into water and carbon dioxide, at which point it can be excreted (primarily via our wees).

Your liver does its best to complete this process expediently; but it stands to reason that there is only so much throughput that it can handle at any given time. If you’re drinking faster than your liver can keep up – by consuming more than the equivalent of 10 grams of ethanol per hour, for example – then the level of un-metabolised ethanol that is circulating in your bloodstream will stack-up as it waits for its turn to be run through the liver. Metabolising all that ethanol (particularly dealing with all that highly-toxic acetaldehyde) takes its toll on your liver and other organs; and the more un-metabolised ethanol that you have circulating in your system waiting to be processed, the more time your brain will be bathing in it. The longer and deeper the bath, the greater the chance that you’ll strike upon a grand idea involving a traffic cone and a church spire.

The way that we define a Standard Drink in New Zealand definitely isn’t perfect. But the fact that it has at least some relationship with how our body processes the booze that we throw at it makes it a metric Shit Tonne more useful (and less arbitrary) than many other health-related guidelines. Our government’s guidance on the number of Standard Drinks we should consume in a week – which again leverage-off the WHO’s recommendations – suggest that men should consume no more than three Standard Drinks a day (two for women; a cruel example of biochemical misogyny), and a maximum of 15 Standard Drinks per week (10 for women). At first reading, these guidelines do seem unrealistically punitive – perhaps a range would be more useful than a threshold – but I do believe that they’re both responsible (in a public health sense) and attainable (in a personal sense). I haven’t gotten there yet – I’m still sitting in the 15-20 range, despite introducing a couple of booze-free days a week – but perhaps having the 15-drink threshold as a loose objective is of some subconscious importance in helping me maintain my bearings. And there are all sorts of fun ways to stay within cooee of the target: last week, a 1-litre rigger of Sawmill’s 4.9% XPA (3.9 Standard Drinks), two pints of McLeod’s 3% Hot Curl Berliner Weisse (2.0) and a well-spaced six-pack of 8 Wired’s 7.2% Hopwired (11.2) saw me get close to the objective (17.1 total). I may have fallen short – but I’m working on it.

I’d like to finish with a challenge: if you aren’t already, I encourage you all to start counting your Standard Drinks. This is likely to be wholly impossible for my sisters and brothers who spend their days on the brewery floor – quality control is an important and necessary part of the gig, a topic that we should think about in more detail another day – but for the rest of you, I challenge you to work out how much you’re drinking each day, and then add-up how much that is over a given week. Thanks to some actually-helpful industry regulation, you can read the number of Standard Drinks right off the side of your bottle; but if you’re drinking at your local pub (or from a rigger that you filled at your local tap-joint) the formula provided in this article will help you sort out how many Standard Drinks are in your glass. I’m unaware of any decent phone apps that can help us do this automatically (please punch me on Twitter if I’m wrong), and while there are a couple of automatic website calculators I reckon a good-old calculator app works just fine.

So there’s your challenge: for the next week or two (or more), record how much you’re drinking in terms of Standard Drinks per day and per week, and then spend just one or two minutes thinking about those numbers. Two minutes thinking-time is plenty: any more than that and you’re just dwelling on it. Whatever the numbers are, you’re only a week away from better ones.